This invention relates generally to electrostatographic reproduction apparatus, and more particularly to devices for loosening and removing residual particles from an image-bearing surface of such apparatus.
Electrostatographic process reproduction apparatus for producing copies of an original document are well known. Such copies typically are produced on suitable receivers through a repeatable process that normally includes the steps of (1) using electrostatic charges in some manner to form a latent image on the surface of an image-bearing member; (2) developing the latent image with developer material that includes toner particles; (3) transferring the developed image to a suitable receiver for fusing; and (4) cleaning the image-bearing surface thereafter by removing residual toner and other particles therefrom in preparation for repeating the process.
The quality of the copies obtained by repeating these steps depends significantly on the effectiveness of cleaning devices employed for removing the residual particles left on the image-bearing surface after image transfer. Such cleaning devices include, for examples, (a) pneumatic brushes as disclosed in U.S. Pat. Nos. 4,851,880 and 4,111,546; (b) magnetic brushes as disclosed in U.S. Pat. Nos. 4,723,144 and 4,601,569; and (c) magnetic sleeves as disclosed in U.S. Pat. No. 4,571,070. Typically, these cleaning devices mechanically contact the image-bearing surface in order to contact and remove residual toner and other particles thereon. Such contact howeve must be slight so as not to disturb the smooth movement of the image-bearing member during the copying process, and so as not to scratch or otherwise damage the image-bearing surface being cleaned.
Accordingly, such apparatus ordinarily will effectively remove only residual particles that are loosely associated with the image-bearing surface, but not particles that are strongly attached to, or embedded in such surface. As disclosed in above-cited U.S. Pat. No. 4,111,546, additional mechanisms such as an ultrasonic vibrator, for example, have been suggested for loosening such strongly attached or embedded particles from the image-bearing surface during their removal by a cleaning device. Ultrasonic vibrators however are relatively expensive, and in addition run a significant risk of introducing undesirable process-disturbing vibrations in the image-bearing member.
An electrostatographic process apparatus, which has an image-bearing member with a soft surface, is particularly more susceptible to this problem of strongly attached or embedded particles. Additionally, the problem is aggravated in cases where the developer material being used comprises toner particles and small, hard magnetic carrier particles. This appears to be so because such hard carrier particles tend to have very fine sharp edges and points, and such sharp edges and points then tend to become deeply embedded in the soft surface of the image-bearing member, for example, during the image transfer step. The problem is also made worse because such embedded particles, being small, may lack the mess in order to make them responsive to pneumatic or ultrasonic attempts to loosen them from such surface.